The present invention relates to a unit for a single-lever mixing valve having a fixed housing, an inner sleeve disposed within the housing, a cage which is rotatable and radially displaceable relative to the housing, a spindle which is swivel-mounted obliquely inside the inner sleeve, engages in the cage and is actuated externally, and with superposed washers having openings, of which one is desired as an inlet valve and attached to the housing and another is designed as a distributor valve and attached to the cage, while yet another is fitted as a shim between the inlet valve and the distributor valve.
Units for single-lever mixing valves of the abovementioned type are known from DE 28 27 236 A1, DE 29 29 199 A1. With these known units the shim can rotate together with the inner sleeve relative to the inlet valve. The distributor valve can rotate radially relative to the shim. Mixing of clod and warm water into mixed water occurs between inlet and distributor valves, while opening and closing of the valve occurs between shim and distributor valve. In the known units there is the risk of so-called spillage: if only a small amount of mixed water is removed, the openings--not exhibiting separate inlet ducts inside the same washer--between shim and distributor valve are extensively closed and if the temperature of the mixed water is selected such that the openings between inlet valve and shim are extensively opened, there may be resulting mixed water reflux in the lower-pressure water feed pipe. Spillage can be overcome by incorporation of reflux valves in the feed pipes. This is, however, not a justifiable expense.